Method and apparatus for the treatment and utilization of superheated steam



J. R. M DERMET METHOD AND APPARATUS FOR THE TREATMENT AND May 21, 1929.

UTILIZATION OF SUPERHEATED STEAM Filed-July 13, 1925 HI I III H I II] NVENTOR irl/r1411? I Patented -May 21, 1929 UNITED STATES PA EN OFFICE." f

-PANY, .OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

mn'rnon AND APPARATUS roe THE TREA MENT Ann urILIzATIon on SUPER- HEATED STEAM. Application filed. July 13,

The present invention relates broadly to power plant practice and equipment, and more particularly to a method and apparatus for the treatment of superheated steam to fireduce it to a condition of saturation, and for the utilization of the saturated steam so produced.

In my co-pending application Serial No. 651,301, filed July '13, 1923, I have disclosed and'claimed a methodand apparatus for desuperheating steam to reduce the superheat therein toa condition of saturation whereby the characteristics of such steam,

be understood that the utility of the invention is not limited in this respect.

At the present time, there is a tenden y in power station operationto employ steam pressures considerably higher than has been customary in the past. Heretofore, the range'of steam pressures has been up to 350 poundsper square inch as a maximum, while now these pressures frequently extend to 550 pounds per square inch. On account of the strength of materials, however, it has not been expedient to increase total steam temperatures much beyond 7 *F. The expansion of steam in a turbine through this pres I sure range from, for instance, 550 pounds gage to one pound absolute, with such a mod erate amount of initial superheat as the strength of materials imposes, produces very wet steam which is inefficient during part of a turbine expansion.

In orderto obviate this objection to the wet steam, a reheat cycle has been develo'ped'inwhich steam with an initial temperature of 750 F. and 550 pounds pressure,

for example, is brought through the turbine and expanded to a ga e pressure of 200 pounds. It is then withdrawn frqm the 1923. Serial No. 651,302.

' turbine, again supe heated, and subsequently returned as superh ated steam to complete the expansion;

Considerations of generation indicate the advisability-of abstracting-steam from various stages of the main turbine for feed water heating. With the steam cycle. involving the resuperheat at an intermediate point in the expansion, the usual stage connections nowexhibit superheated steam, whereas under the previous cycle of operation the steam on the stage heat economy in power connections" was saturated. This superheated steam, as such, produced withpresent day turbine designs, does not give eflicient heater performance. a The invention there fore embodies the treatment of this steam .in'such manner as to insure high conductivity. p a p In the accoinpahying drawings there is shown, for purposes of illustration only, in a more or less diagrammatic manner, a preferred embodiment of the present invention, itbeing understood that the drawings do-not define the limits of the invention, as changes may obviously be made in the construction and operation disclosed without departing from the spirit of the invention or scope of m broader claims. 4

n the drawings Figure l is a view partly.

prise a heater '2, preferably of the closed type, having a condensate outlet 3 and a" cooperating desuperheater 4. This desuperheater, which may be of the construction covered in my co-pending application before referred to, has an inlet 5' and an outlet 6,

the inlet and outlet, respectively, preferably being at substantially diametrically opposite sides of the 'desuperheater chamber 7. Within this chamber, and so located as to intercept the path of travel of the steam, is a porous body8 pei'vious to the passage of steam and preferably confined between perforated plates 9..

. While the particularconstruction of the l I desuperheater may be'varied, I have found I l that'eificient. results may 'be obtained by employing perforated Monel plates for the bafiles 9 and wire mesh of Monel wire for the body, 8. This entire body may .be in the form of a cartridge adapted to be bodily inserted in or removed from the chamber 7 i The outlet 6 leads through 'a suitable confnection to the vapor inlet 10 of the heater 2. while the condensate outlet 3 from the heater leads to a manifold 11 provided with a series of perforations or nozzles 12 so positioned as, to supply the condensatetothe porous body 8.

In operation of the apparatus, it will be apparent that superheated steam passes from the inlet 5 through the porous body 8 to the heater, wherein it gives up its heat to the feed water supplied thereto, as is customary in the art, and is condensed. The amount of condensate so formed will bear a definite relation to the amount of steam supplied to the heater. This condensate will in turn pass to the desuperheater through the nozzles 12 and maintain a film of water over the surface of the porous body therein. This Water, supplied for do superheating purposes, will in large part be evaporated by the superheat in the steam, thereby increasing the total volume of the steam while decreasingthe total temperature, but without reducing the pressure. The steam therefore leaves the desuperheater as saturated steam, yielding considerably higher conductivity than would otherwise be possible, as the latent heat is immediately available for heating purposes within the heater.

In the event of any excess in the amount of water supplied to the desuperheater, such excess may easily drain from the apparatus through the connection 13.

' This. organization of apparatus has been found to be highly eflieient from a standpoint of. installation and performance. Where the water required for desuperheat ing is brought to the desuperheater by means of an independent external connection, ashas heretofore been contemplated,

' there has. beenconsiderable risk due to the possibility of any excess of water flowing back into the turbine. As large steam turbines of the type now being installed fre quentlycost in the neighborhood of 2. mill1on dollars, the risk involved becomes considerahle. By the present invention, this risk is entirely eliminated, as the amount of desuperheating water supplied to the dc superheater bears a definite relation and is automatically proportioned to the amount of steam to be desuperheated and to the turbine load. This is necessarily true for.

the reason that the only source of water for the desuperheater is condensate froni' the heater, and the only source of this condensate is steam which has first passed through the desuperheater. When the steam is shut oil from the turbine, necessarily it'will he shutofl from the extraction connection and no water supply to the desuperheater will be available. 7 This constitutes one very advantageous feature of the present invention. Furthermore, the presence of moisture, cold steam lines, etc., will provide sufiicient wet steam at the start-up to enable the apparatus to come immediately into operation. Furthermore, it is customary, due to operating necessity, to start the complete unit on saturated steam and subsequently create the condition of superheat gradually after the apparatus is in operation. It will be apparent, therefore, that the desirable selfstarting features of the apparatus are ensupplying to said, desuperheater desuper heating Water not in excess of an amount equal to the condensate which could be formed from the steam fed to the desuperheater, and substantially equal in amount to the condensate which could be formed from the steam fed to the desuperheater.

3. In the method of treating and utiliz ing steam, the steps consisting in passing superheated steam through a desuperheater and the resulting saturated steam mto a heater, condensing the steam in the heater,

and feeding condensate from the heater to the desuperheater fordesuperheating purposes.

4. In'the method of treating and utilizing steam, the steps consisting in feeding superheated steam to a desuperheater, feeding the steam from the desuperheater to a heater in saturated condition, condensing the steam in the heater and supplying to saiddesuperheaterfor desuperheating purposes only the condensate formed by the condensation of said steam in theheater.

5. Power plantapparatus comprising a closed heater, a desuperheater supplying steam thereto, and means for bringing condensate from the heater into contact in divided form with steam desuperheater.

6. Power plant apparatus comprising a passing through the closed heater, a desuperheater having its outlet leading to the vapor inlet of the heater,

means intersecting the flow of steam through.

arrears -1neans 'for leading condensate to said-'- means.

7. Power plant apparatus comprising a closed heater and a desuperheater supplybringing the same ,into mtimatecontact with ing steam thereto, said heater having a-'con-' densate outlet leading tothe' desuperheater and constituting the sole source of liquid supply to the desuperheater, and means.

pervious to the passage of steam and intersecting the steam flow for receiving said condensate and bringing'the steam and the condensate into intimate contact.

8. Power plant apparatus comprising a heater, a desuperheater, supplying steam thereto, said heater having a condensate outlet leading to the desuperheater, and means of steam and intersecting the steam flow through the desuperheater for receiving condensate from said outlet and bringing the condensate and steam, into intimate contact.

' v 9. Power plant apparatus comprising a closed heater, a desuperheater havingjts out.- let leading to the vapor inlet of the heater, and of sufficient size to conduct to the heater all of the steam received by the desllperheater plus an additional ameunt represented by the evaporation of water within the desuperheater', and a condensate outlet for supplying desuperheating water from the heater to the desuperheater.

10. Power plant apparatus comprising a closed heater, a desuperheater havingits outlet leading to the vapor inlet of the heater and of suflicient size to conduct to the heater all of the steam received by the .desuperheater plus an additional amount represented by the evaporation of water therein, said heater having a condensate outlet for supplying desuperheating water to the deheater pervious to the passage of steam for receiving said desuper eating water and the steam. v

superhe'ater, and means within the desuper-i myhand.

lit-Power plant apparatus comprising a desuperheater having an inlet for superheated steam, and means .for supplying to said desuperheater in contact with t e superheated-steam desuperheatingwater in the forin of condensate.,formed from said de-. superheated-steam and in an amount such that the superheat of the steam is destroyed without substantially decreasing the heat quantity of the steam.

12. Power plant apparatus comprising a desuperheater having an inlet for' superheated steam, an outlet 'for saturated steam and a heater for receiving desuperheated steam from said: outlet, said heater having a condensate outlet conducting such condensate as desuperheating water in divided condition to said desuperheater in contact with the steam. in said desuperheater pervious to the passage 1 13. In the method of treating and utilizin'g'isteam, the steps consisting in desupertiallyas great aheat quantity in vapor state, condensing the: desuperheated steam by -.utiliz'i ng the same for heating pur oses, and

ing steam, the stepsconsisting in desuperiheatin'g steam while maintaining substa heating superheated steam while .maintaining substantially as great a heat quantity in vapor state, passing the desuperheatedsteam to a heater, condensing the steam in said heater, and sup lying the condensate: so formed for desuperheating the steam supplied to the heater.

- 15. In the method of treating and utilizing steam, the steps consistin in desu erheating superheated steam s'ation thereof, passing the desuperheated steam to a heat exchah er and supplying the In testimony whereof I have JQHIfBQMoDERMETJ out con en'- condensate from said eat exchanger to the 'desu erheater for desuperheating the steam supp ied to the heat exchanger.

hereunto set 

